In the Viking era starting c. 793, the Norse raiders often captured and enslaved weaker peoples they encountered. In the Nordic countries the slaves were called Thralls. The thralls were mostly from Western Europe, among them many Franks, Anglo-Saxons, and Celts. There is evidence of German, Baltic, Slavic and south European slaves as well. The slave-trade was one of the pillars of Norse commerce during the 6th through 11th centuries. The practice came to an end when Catholicism became widespread throughout Scandinavia. As in the rest of Catholic Europe, the Church held that a Christian could not morally own another Christian. As the Thrall system died out, it was not replaced with the Serf system in most of the region